Abstract
Freshwater fishes inhabiting agricultural channels change their distribution area according to the life history stages, and the fish habitat can change among seasons (i.e., reproductive season, growing season and wintering season, etc.). Thus, to evaluate the effectivity of the restoration methods for fish, we have to understand the seasonal difference of habitat preference by fish and then reflect the knowledge to restoration methods in agricultural channel improvements. In this study, we conducted fish samplings in restoration areas, as well as non-restoration areas, of an agricultural channel, to clarify the difference of habitat preference by fish between the active and wintering seasons. The results of multiple regression analysis indicate that important environmental factors for fish habitats are different between the active and wintering seasons and that the factors are the water depth diversity, average water velocity and minimum water velocity in the active season and are the maximum water depth, average water velocity and rate of vegetation in the wintering season. These results indicate that fish inhabitation areas in the agricultural channel are different between the active and wintering seasons. To create restoration areas for fish habitats in agricultural channel improvements, we need to consider the difference of the habitat preference by fish between the active and wintering seasons.
